saa7130basedtvtunercardunderlinux

SAA7130 TV tuner card under Linux. How To.

saa7130 in Linux Jobin Augustine

I thought of writing this page because lot of people are
facing problems in installing with their TV tuner cards based on Philips chip
saa7130.it took me almost 2-3 months search to get it
working perfectly.Primarily because i was using a old Linux kernel
which got driver with less card support

We should remember that the module saa7134 is written in
a generic way. so that it will work with saa7130 also.I
should say saa7130 is a scale-down version of saa7134. Please make sure that you got tvtime installed in your system before doing
anything.because i feel this is the user friendly
application for doing all the experiments.when we are
fighting with hadware problem we cannot concentrate on application
issues.

Understanding your card - the hardware.

Normally a TV tuner card can be divided into 2 section. the Video decoder and the Tuner. In this article i am concentrating on decoder with PHILIPS SAA7130 chip. using lspci and dmesg make sure that card got a Philips SAA7130 chip. its very easy to find out even you can directly look at the tuner card. But its not that simple to identify the tuner. in most cards i found that the manufactures buts big sticker on the tuner. since tuner sits inside a metalic box case, it is the right place to put the sticker :). either you can remove the sticker to findout the exact make: The model number. other option is the ugly solution the card manufacuter might have given a windows driver CD. install the card in windows. then you can get the driver details from the windows driver. I done it both the ways to confim that what i know is correct. :)

Loading Kernel Module - saa7134

all recent kernels comes with generic Loadable Kernel
Modules (LKM) for SAA713* chips (SAA7130,SAA7133,SAA7134 etc).this module is called saa7134. there are other submodules
(dependancy) like saa7134_alsa, saa7134_dvb, tuner etc.
You can load a module like:

modprob saa7134 card=3

But many times your system will be already loaded this
module to kernel with wrong parameters, so you need to remove the existing
module if any like

rmmod saa7134_alsa saa7134_dvb saa7134

after this you can load the module with right
parameters. once you can load the module with correct parameters like card and tuner, your card
should be working fine. To get a complete list of parameter a module can accept
use the modinfo command

>modinfo [option] saa7134

-d, which displays a brief description of the module,
and -p, which lists the parameters the module supports

now you can load the module like

modprobe saa7134 card=116

if you are using a Mandrake linux or PcLinuxOs the you
have a GUI to do so (HardDrake). but this is not important.

after seeting this values in modeprobe.conf, just load
the module.

>modeprobe saa7134

Identifying the card

I experimented with different values for card. in the
card list, you can select any card with saa7130 to get the video. for example 3,10,21,42 etc should work fine for card. ,

Other than this trial and error method, there is an
alternate way. by looking in to Kernel source. Either you can download the full
source from kernel.org or you can browse though the source online using sites
like:

Identifying the Tuner

Here one thing we need to remember the driver saa7134 is written such a way that
Each card got associated tuner spec also. (the default tuner for each card)
If you have default tuner, you may not required to override this by specifing like tuner = 37
For getting a sutable value for tuner also 2 methods the trial and error and systematicaly looking at the source code
By trial and error i am able to find out that values like 37,55 are working fine for me.
if you want to look in to he source code, here is the method.
first we need to look the place where linux is identifing the card and the tuner
this file is located in /drivers/media/video/tveeprom.c of the source tree alternatively :
http://www.gelato.unsw.edu.au/lxr/source/drivers/media/video/tveeprom.c
here most of the tuners are listed. for example, i have "TCL 2002MB 3" tuner.
in this file we can find that the tuner is pointing to TUNER_LG_PAL_NEW_TAPC
which is defined in source/include/media/tuner.h alternatively you can look at
http://www.gelato.unsw.edu.au/lxr/source/include/media/tuner.h
where you we can see that this tuner is identified as number 37.
which perfetly matches my trial and error experiment
How to set the parameter values?well. just open /etc/modprobe.conf and
place the line ( if it is ubuntu or debian based distribution the file will be /etc/modprobe.d/options options saa7134 card=3 tuner=55 in ubuntu, the file name is: /etc/modprobe.d/options or in
ubuntu you can directly load the options when you are loading the module
like:modprobe saa7134 card=3 tuner=55 gbuffers=4

from ubuntu 9.04 onwards we need to have a file saa7134.conf in /etc/modprobe.d with same line.

before this, you may have to
remove the already loaded modules like:rmmod
saa7134_alsarmmod saa7134

Using TVTime.

once the you laoded the module, now you can connect the cable to the tv tuner card. and scan for channels.

>tvtime-scanner

now all channels will be scanned and stored in the stationlist.xml file.

at this point you should be able to use the TVTime application.

>tvtime

saa7130 video

You will not see any problem in getting
video output from the card. because the video section is same for
almost all saa713x chips / cards.

saa7130 audio / sound

Many times audio is the difficult part to get working. But the funniest fact is that SAA7430 is not doing any audio processing.
Infact that is the major differece between SAA7130 and its siblings like SAA7133,SAA7134,SAA7135 etc.
i think its worth to understand why audio is not working.
This chip just allows the audio to pass though the chip untoched. So what could be blocking the sound?
I had to go though the datasheets provided by Philips to understand some facts,
So this chip do not have the feature to place the audio to system bus (like PCI). it just allows the sound to passthough (analog) and that will be availble on the card (audio out).
So SAA7130 tuner cards will ship with a 2 end connector to connect its audio out to your line-in.
we need to connect that audio-out to line-in of the sound card to get the sound to system.

so the end result is: modules like saa7134_alsa or saa7134_oss are not requied and will not work for saa7130 cards
I know lot of people still fighting with ALSA tools like arecrod to get the sound from this card. They may get read errors from the device.
So you need not go behind arecord or sox. because your TV sound is not there. and you are looking for something does not exists :)

Before starting any experiments, please connect your speaker/aplifier input to audio-out of the tv-tuner card bord directly.
The best way is to directly plug your headphone to the tuner card.
this is to ensure that the sound is not muted inside the sysetem.
if you connected to amplifier please keep the volume very less otherwise you may loose your ear drum once you rectify the audio problems. :)

You may find that by default TV sound is muted. why so?
here is the answer. That is because of the default behavior of SAA7130 chip. it should be like that
because SAA7130 relies on loop back cable to your sound card. so you are loosing your line-in port for other purposes
to address this problem SAA7130 accepts 2 audio in connections (both sterio). one set of pins for TV audio from the Tuner / IF section.
another is to provide line-in fuctionality. SAA7130 allows you to connect your actual line-in requiremnts like input from your cassete player
many TV cards do not have line-in ports. but the chip sitting in the card provides that feature. sounds nonsence right?.
So by default SAA7130 connects it line-in input to its passthough output. and TV sound is disconnected.
Now let me tell you the problem you need to rectify. we need to initalize the card with right flags in place to connect its tv audio to its passthough output

So I started my efforts to findout a suitable card number, which can put my cards internal switch to pass the audio from TV to passthough output
it was a furstrating brute force method and spend long hours...many times ended with system reboots.. many times got noice with very low audio in the backgroud...finally i arived at a card number which can put the right switch for audio. Now i am getting a very clear audio out!